1. Field of the Invention
The present invention relates to a vibration isolating apparatus which used to prevent transmission of vibrations from a vibration generating portion, the apparatus being applicable to a mount for supporting a member such as an engine or the like which generates vibrations.
2. Description of the Related Art
For example, in a conventional structure, a vibration isolating apparatus serving as an engine mount is disposed between an engine, which is a vibration generating portion of a vehicle, and a vehicle body, which is a vibration receiving portion of the vehicle. Vibrations generated by the engine are absorbed by the vibration isolating apparatus and are prevented from being transmitted to the vehicle body.
A structure in which an elastic body and a pair of liquid chambers are provided within the vibration isolating apparatus and a restricted passage serving as an orifice communicates these liquid chambers is known as such a vibration isolating apparatus. When an engine installed in a vehicle is operated so that vibrations are generated, the vibrations are absorbed by the damping function of the elastic body, the viscous resistance of the liquid within the orifice communicating the liquid chambers and the like, so that transmission of the vibrations is prevented.
An example of such a structure will be described hereinafter with reference to a vibration isolating apparatus 110 shown in FIGS. 5 and 6.
As shown in these drawings, an elastic body 118 made of rubber is disposed between and adhered by vulcanization to an outer cylindrical metal fitting 120 and an upper mounting metal fitting 116. Further, the outer cylindrical metal fitting 120 is inserted into a bracket 114, and a rebound stopper metal fitting 112 is caulked to the bracket 114.
Further, a liquid chamber 124 is provided between a diaphragm 122 disposed within the outer cylindrical metal fitting 120 and the elastic body 118. A separating wall member 130, which has an orifice 132 and separates the liquid chamber 124 into a pair of liquid chambers 124A and 124B, is disposed within the liquid chamber 124.
Accordingly, in the vibration isolating apparatus 110, the liquid within both the liquid chambers 124A and 124B flows through the orifice 132 communicating the liquid chambers 124A and 124B with each other, so as to reduce the vibration.
However, in assembling the conventional vibration isolating apparatus 110 described above, when the entire outer periphery of the outer cylindrical metal fitting 120 is inserted into the bracket 114 by press fitting, since a great force is applied to the outer cylindrical metal fitting 120, the separating wall member 130 or the like is deformed, and the ability of the separating wall member 130 to seal the liquid chambers may deteriorate.
A measure to counter this problem has been considered in which the outer cylindrical metal fitting 120 is inserted into the bracket 114 with a lower portion 120B of the outer cylindrical metal fitting 120 not being press fitted and only an upper portion 120A thereof being inserted into the bracket 114 by press fitting. Thereafter, the sealing of the liquid chambers is performed by suitably connecting the lower portion 120B of the outer cylindrical metal fitting 120 and the bracket 114 by means of a drawing process.
However, in this case, the lower portion 120B of the outer cylindrical metal fitting 120 shown in FIG. 7 is inclined toward an inner peripheral side as shown by the two-dot chain lines due to the effects of the upper portion 120A of the outer cylindrical metal fitting 120, so that the lower portion 120B is not smoothly deformed. Accordingly, the separating wall member 130 is unstable within the outer cylindrical metal fitting 120 such that the sealing between the pair of liquid chambers 124A and 124B by the separating wall member 130 may be insufficient and the sealing of the liquid chamber 124 itself may be insufficient such that there is a risk that the liquid within the liquid chamber 124 may leak to the exterior thereof.
Further, when the vibration isolating apparatus is being assembled by the above method, since the position of the separating wall member 130 is restricted only by a step 118A of the elastic body 118 which is elastic and flexible, the separating wall member 130 is moved in the vertical direction in the drawing or the separating wall member 130 rides onto the elastic body 118. As a result, it is difficult to stably seal the pair of liquid chambers 124A and 124B by the separating wall member 130.
A measure to counter this problem has been considered in which a vibration isolating apparatus 210 (see FIG. 8) is provided which is structured such that a pair of outer cylindrical metal fittings 220A and 220B are employed as the outer cylindrical metal fitting, and a separating wall member 230 having an orifice 232 is caulked between the pair of outer cylindrical metal fittings 220A and 220B so as to be disposed within a liquid chamber 224. However, in this vibration isolating apparatus 210, since a sealing portion 230A of the separating wall member 230 is disposed at the outer peripheral side of the vibration isolating apparatus 210 and is sealed by caulking, the caulked portion projects toward the outer peripheral side of the vibration isolating apparatus 210.